The present invention relates to a new diagnostic and therapeutic form of radioactive compounds and more particularly to an improved encapsuled form of diagnostically and therapeutically useful radioactive compounds.
Radioactive compounds, such as sodium radioactive iodide (I-131), have been dispensed by measuring out, usually by remote control suitable volumes of a radioactive compound in an aqueous medium. For diagnostic uses in particular, most of the radioactive material is given orally and for such use it was customary to measure or pipette the aqueous solution of the radioactive compound into a cup or glass immediately prior to administering orally to the patient. The foregoing method of administering radioactive materials resulted in serious contamination of glassware and other equipment as well as the mouth and esophagus of the patient.
The foregoing disadvantages were in part overcome by adding an aqueous solution of a radioactive compound to a gelatin capsule which is filled with sodium phosphate, the latter serving to remove part or all of the water to form a hydrate with the result that the radioactive material is disposed on a fine, fluffy powder confined within the interior of the said capsule. Experience showed that the latter capsules were not well suited for this purpose because the action of the water on the gelatin capsules during filling causes the development of irregular areas in the capsules. Moreover, when the capsules are damaged or broken, the remaining capsules and adjacent container becomes seriously radioactively contaminated. The latter contamination is even more serious if the breakage of the capsules occurs during the handling of the capsules while being given to the patient.
Tabern et al. U.S. Pat. No. 2,911,338 discloses providing a gelatin capsule or capsule of other thermoplastic, water soluble, non-toxic material which has disposed interiorally as an integral part thereof or adsorbed on the interior wall a therapeutic or diagnostic dose of an organic or inorganic radioactive compound, such as sodium radioactive iodide. Tabern discloses that it is possible to provide a capsule composed of a non-toxic therapeutic water soluble material having interiorally disposed as an integral part thereof a therapeutic or diagnostic dose of a radioactive compound by forming a solution of the said radioactive compound in a relatively volatile essentially non-aqueous organic solvent, depositing a carefully measured volume of the said solution in an empty capsule or half thereof, and completely removing the solvent to leave the radioactive compound adsorbed on the inner walls of the capsule as a firmly attached integral part thereof.
The present invention provides a pharmaceutical radioactive capsule of improved shelf life.